Method for producing elements from phase change material

ABSTRACT

The object of the present invention is to provide a drill for producing a deep hole that does not produce bend of the hole during cutting. A drill body  1  is spirally provided with a pair of cutting edges  3 . The cutting edges  3  are spaced at about 180 degrees apart around a core  1   a  of the drill and the edge line  3   a  of a tip section of the cutting edges  3  is depressed toward a core  1   a  of the drill. When the outside dimension of the drill is 7.4 mm, an angle between the edge line  3   a  and a line perpendicular to the core  1   a  is 5 degrees and the core thickness (t) is 2.96 mm. Further, the drill is provided with a guide section  4  for preventing bending in the case of a cutting operation. The guide section  4  is provided on a heel side on the same circumference as that on which the outer end section of the cutting edges  3 , 3 passes.

TECHNICAL FIELD

The present invention relates to a drill for producing a deep hole in acylinder block, a crankshaft, and the like of an engine.

BACKGROUND ART

One example of a drilling tool is proposed in each of the followingPatent Documents 1, 2 and 3.

Patent Document 1 discloses a tapping screw having a drill cutting edgeprovided at the tip section and an end mill cutting edge formed next tothe drill cutting edge. In this prior art, the tip section of the drillcutting edge is formed to cause the core section to protrude in theaxial direction.

Patent Document 2 discloses an end mill of which the tool body isprovided with first and second flutes, wherein the first flute isprovided with a first peripheral tip and a central tip, while the secondflute is provided with a second peripheral tip. In this prior art, thecutting edge lines of a tip section of the first and second peripheraltips are formed to be depressed toward the tool core.

The difference between the drill and the end mill is now clarified. Thedrill has the cutting edge only on the tip and is used for drilling andchamfering operations. On the other hand, the end mill has an endcutting edge and a peripheral cutting edge and can be used for drilling,grooving and a side cutting operation, but a shallow hole can only bemade because the tip room is narrow.

Patent Document 3 discloses a drill of which the spiral angle of thecutting edge is gradually decreased toward a shank. In this prior art,it is shown that the tip edge line of the cutting edge is depressed.

[Patent Document]

Patent Document 1: Japanese Utility Model Publication No. Hei 6-18710

Patent Document 2: Japanese Utility Model Publication No. Hei 6-254711

Patent Document 3: Japanese Unexamined Patent Publication No. Hei7-40118

FIG. 5 explains an example in which a deep hole is made in a cylinderblock with a conventional drill (point angle: 118 degrees) of which thetip of the cutting edge is projecting. As shown in FIG. 5 (a), thecylinder block is formed with a lower hole (i.e., a mold-release hole)in the case of casting. If cutting proceeds in such a condition in whichthe center of the lower hole is not in line with the core of the drill,a difference is caused in the radial force even though a cutting forcereceived from the cutting surface is the same as shown in FIG. 5 (b). Asa result, a sudden hole-bending may be generated as shown in FIG. 5 (c).

On the other hand, when the tip section of the cutting edge is formed tohave a depressed shape, the bending can be improved because the tipsection does not follow the lower hole in the case of cutting and therectilinear propagation is good. However, bending is readily generatedwhen the hole to be cut is deep because there is still a difference inthe radial force.

DISCLOSURE OF THE INVENTION

To solve the above-mentioned problem, according to the presentinvention, there is provided a drill for making a deep hole in which theedge line of a tip section of a spiral cutting edge is depressed towardthe core of the drill and a guide section is provided on a heel side onthe same circumference as that on which the outer end section of thecutting edge passes in the tip section of the drill.

In this manner, by providing the guide section, the drill is supportedat four points including the cutting edges and as a result, bending inthe case of making the deep hole can be controlled. It is also possibleto provide the guide section with a diamond edge.

Further, to improve the rectilinear propagation of the drill withoutfollowing the lower hole, it is desirable that the concave angle of thetip section of the cutting edge be between 0 and 10 degrees, forexample, be about 5 degrees.

Still further, the standard core thickness of the drill having a generaloutside dimension of 7.4 mm (=D) is 1.48 mm or less (0.2 D). However, inthis case, the core thickness is overcome or affected by the radialforce produced in the case of producing the deep hole and as a result,bending is readily produced. It is therefore desirable that the corethickness be 2.22 mm (0.3 D) or more, for example, be about 2.96 mm (0.4D).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a whole view of a drill for making a deep hole according tothe present invention;

FIG. 2 is an enlarged view of a tip section of the drill for making adeep hole according to the present invention;

FIG. 3 is an end view of e tip section of the drill for making a deephole according to the present invention;

FIG. 4 is an end view similar to FIG. 3 showing another embodiment (witha diamond cutting edge provided); and

FIG. 5 (a) through (c) are views explaining a conventional problem.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be describedwith reference to the accompanying drawings. FIG. 1 is a whole view of adrill for making a deep hole according to the present invention. FIG. 2is an enlarged view of a tip section of the drill for making a deep holeaccording to the present invention and FIG. 3 is an end view of the tipsection of the drill for making a deep hole according to the presentinvention.

A drill for producing a deep hole comprises a drill body 1 and a shank2. The drill body 1 is spirally provided with a pair of cutting edges 3.The cutting edges 3 are formed at opposing positions spaced apart byabout 180 degrees around a core 1 a of the drill and the edge lines ofthe tip section of the cutting edges 3 are depressed toward the core 1 aof the drill. An angle formed between the edge line 3 a (the edge lineof the cutting edges 3 in the outer end section) and the lineperpendicular to the core 1 a is 5 degrees. In the figure shown here,the core thickness (t) is 2.96 mm (0.4 D).

The drill according to the present invention is further provided with aguide section 4 for preventing bending in the case of cutting. The guidesection 4 is provided on a heel side on the same circumference as thaton which the outer end section of the cutting edges 3, 3 passes. In thismanner, a stable cutting operation can be performed by four pointsupport of the cutting edges 3, 3 and the guide sections 4, 4.

FIG. 4 shows a view similar to FIG. 3 showing another embodiment In thisembodiment, diamond edges 5, 5 are provided at the tip section of theguide sections 4, 4 to have a structure that can be diverted to areaming operation.

INDUSTRIAL APPLICABILITY

As described above, the drill according to the present invention isprovided with the guide section so that the drill can have a self-guidefunction and the tip section of the cutting edge is depressed toward thecore so as not to follow the lower hole for smooth rectilinearpropagation. Further, since the core thickness is increased for higherrigidity, generation of bending can be prevented even though adifference is caused in the radial force by the displacement between thecenter of the lower hole and the core of the drill when a deep hole ismade in a crank shaft, a cylinder block and the like.

1. A drill for producing a deep hole comprising a spiral cutting edgewherein the edge line of a tip section of the cutting edge is depressedtoward a core of the drill and a guide section is provided on a heelside on the same circumference as that on which an outer end section ofthe cutting edge passes in the tip section of the drill.
 2. The drillfor producing a deep hole according to claim 1, wherein a concave angleof the depressed tip section of the cutting edge is between 0 and 10degrees.
 3. The drill for producing a deep hole according to claim 1,wherein when the outside dimension of the drill is D, the core thicknessof the drill is 0.3 D or more.
 4. The drill for producing a deep holeaccording to claim 1, wherein the guide section is provided with adiamond edge.
 5. The drill for producing a deep hole according to claim2, wherein when the outside dimension of the drill is D, the corethickness of the drill is 0.3 D or more.
 6. The drill for producing adeep hole according to claim 2, wherein the guide section is providedwith a diamond edge.
 7. The drill for producing a deep hole according toclaim 3, wherein the guide section is provided with a diamond edge. 8.The drill for producing a deep hole according to claim 5, wherein theguide section is provided with a diamond edge.